Soni capitulo 8 y 9

Unit IX. Motion Programs

Objectives
1. To identify applications of custom-inado motion programs in cam ilcsign
1. To synthesize motion programs using (lie analylical lceliiik|ucObjective 1
To identify applications of custom-made motion programs Activities
• Read the material provided below, and as you read:
a. Describe the criteria to test a given motion program.
b. Ñamethe characteristics of the following motion programs:
constant velocity motion program
constant acceleration motion program
simple harmonio motion program
modified harmonio motion programcycloidal motion program
cubic curve motion program
polynomial curves for follower motion program
trapezoidal motion program
c. Demónstrate their application in designing cams.
d. Ñame the advantagesand disadvantages of using custom-made motion
programs.
• Check your answers to the oompetency items with your instructor. Reading Material
A cam is usually fabricated using the displacementprogram. However, such a displacement program is arrived at by using a series of boundary conditions describing displacement, velocity, acceleration, and jerk at different intervals of cam rotation angle.The quality of a motion program is measured from the different types of boundary conditions that it satisfies. If a displacement program is available, then the velocity, acceleration, and jerkprograms of the follower are obtained by taking time derivative of the displacement program. Thus, if s describes the displacement at any time t, then
Velocity = Vdt in./sec

Acceleration
In thissection, we will study several different motion programs which are synthesized in the part by other kinematicians and recommended to adopt in cam dejjgn when special requirements are satisfied. Ourpurposeis to determine the situations when these programs could be best put to work. A good working knowledge of the existing motion program will save time and labor from synthesizing some unwanted motion...